EVIDENCE FOR AN ANTIFERROMAGNETIC TRANSITION IN A ZEOLITE-SUPPORTED CUBIC LATTICE OF F-CENTERS

Evidence for a bcc lattice of F centers in sodium-electro-sodalite (SE S), synthesized by exposing dehydrated sodalite to sodium vapor, is pr esented. A high electron spin density in SES produces isotropic contac t shifts in nuclear magnetic resonance (NMR) spectra of the framework nuclei whose magnitude is a discrete function of local electron densit y. Strong exchange coupling between unpaired electrons gives rise to a n antiferromagnetic phase transition in SES at T-N = 48 +/- 2 K, provi ding the first example of an s-electron antiferromagnet.